photokaboom

Learn Photography

Photoshop Elements >

JPEG Quality Levels

0 through 12

With Photoshop Elements, you can select a JPEG quality level from 0 to 12.

If you select 0, the JPEG is saved as a small file.

If you select 12, the saved file is large.

q

Compression

When you select the quality of the JPEG file that you're about to save, you're deciding how much compression to use.

The compression makes JPEG files smaller.

Lossy Compression

JPEG files use lossy compression.

Some of the pixels are discarded when the photograph is saved.

Lossless compression doesn't discard pixels.

It makes the file smaller by changing . . .

1 00000000000000000000 1

to . . .

1 20(0) 1.

The twenty consecutive zeros become 20(0).

What's Discarded?

JPEG compression is based on what we see.

We're more sensitive to contrast variations, than to color  variations.

So, color information is discarded more than contrast information.

The contrast variations we can see have to be large.

We don't see fine variations in contrast.

So, fine contrast variations are discarded.

Example

Let's say you have a photograph of a chess board on a picnic table.

The sky in the photograph, with many fine contrast variations, can be compressed.

The chess board, with many large contrast variations, can't be compressed as much as the sky.

The sky is high frequency variation, the chess board, low frequency.

To see the difference in high and low frequency variations, go to High Pass & Gaussian Blur Filters Compared with Step Wedges.

Which Quality Level?

Smaller files:

• Enable web pages to load more quickly.

• Allow photographs in e-mails to be sent and downloaded more rapidly.

Larger files are better for making prints.

Since most e-mail clients have a feature for making files smaller, you can probably save your files at the highest quality setting, 12.